In recent years, it has been proposed to provide an electronic money system in which the transfer of electronic money is performed by communication between IC cards in which electronic money is stored. Each of the IC cards used in this system includes a microprocessor which has a communication function inside, and a memory made from an EEPROM or the like which stores a processing program and the balance of electronic money. Electronic money can be transferred from one IC card to another by using a dedicated terminal or via the electronic money system which has terminals provided at banks, stores, individual residences and the like that can be arbitrarily connected to each other via communication lines.